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Posts: 9
Reply with quote  #1 
Hey all,

I recently turned my porch into a sunspace and have been very much enjoying the free winter heating here in the southern hemisphere.

However, I've noticed that the heat doesn't seem to flow much to other rooms of the house.  Here's a basic sketch on the house: [house%20mock] On a day of full sun, the sunspace gets to about 33 degrees celsius, the lounge to about 24 degrees celsius.  The house faces north so the dining gets some heating from the front window but this room stays a few degrees below the lounge. The back rooms stay cooler still.

I have large double french doors which I fully open to allow heat from the sunspace into the lounge.  These take up a good 3/4 of the area of the south wall of the sunspace.  Otherwise, the only airflow to the back rooms is down the corridor.

So, I'm wondering whether installing vents to connect the back rooms to the front and maybe even from the sunspace into the dining space will help to get the heat moving around better.  Any tips on how large the vents would need to be to get a nice convection current going through the house?

I'm also considering turning the garage on the east side of the house into a sunspace so am curious in general to know what can be achieved passively in terms of hot air transfer.



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Posts: 2,240
Reply with quote  #2 
Hi, Simon,

To transfer the heat, you have to transfer AIR !

So before you go cutting vents, the 1st thing to do would be to crack the DINING window OPEN to create a draft through from the LOUNGE, into the Kitchen area: the connecting door obviously wants to be OPEN...

You would also need to let AIR in to the sunspace, of course ! This means sacrificing some glass area, for some air intake...
(A side window in the sunspace would be ideal if there is one...)

You could also try blowing room air at the sunspace window, using a simple desk fan, to pick up more heat off the glass...

A ceiling fan in the lounge would also be an advantage, pulling the air down...

Opening these windows should not be a problem as it is presumably a sunny day anyhow...

Keep the double lounge doors open like you are doing...

The second thing you could envisage, would be to set up a second (floor-level) (desk) fan, somewhere safe (for children, cats etc.), blowing from the Lounge towards the Kitchen, to help the circulation along.

Warming the bedrooms would be a tougher challenge.

For an initial ductless approach, you would need to crack open the bedroom windows, and blow air down the corridor, the bedroom doors being open.  This will be lost air - it exits the bedroom window.  You should not need an enormous flow, experiment with it.
(If the bedroom windows are closed, the air will not move...).
You should only need low-grade heat for the bedrooms in any case...

If you make another sunspace on the garage, you should be laughing!

To get the whole system to work, it would need careful balancing of degrees of opening of Sunspace, Dining and Bedroom windows, but it should work OK.

You could try reading THIS, it is an excellent article for what you are trying to do ("ZONE HEATING...")


(1)  "Heat goes from hot to cold, there is no directional bias"
(2) It's wrote, "voilà" unless talking musical instruments...

Posts: 9
Reply with quote  #3 
Thanks a lot for the reply, G_H.

So, it sounds like passive is not going to cut it in this case?  Is that because the convection current within the house wouldn't be able to move enough air?

Getting air into the sunspace is something I was thinking about.  I may actually get that for free because there were some slight gaps at the bottom of the glazing due to some unevenness in the concrete floor of the porch.  They are just small gaps and I had blocked them off with small sand bags assuming that would be better but it sounds like they might be exactly what I need.  I'll have a go at unblocking them and see how that goes.

I think the problem with opening windows is that there's often nobody at home during the day and by the the time somebody gets home (at least in winter) there would be an hour or two where the windows would have been open but with no sun shining.  I would lose some heat out the windows at that time.

I think the garage has a lot of potential as both a sunspace and also as for thermal storage (I'm thinking of some water-filled 44 gallon drums, water wall retrofit etc).  
Here's the house diagram with garage:
[house%20mock%20with%20garage]Opening the kitchen window would allow direct air transfer between kitchen and garage, however there is currently no air channel between the back bedroom and the garage.  So, once again I'm wondering whether vents in the walls between the garage and back bedroom would give me enough air flow to get some heat into the bedroom when the garage is heated up.  Any thoughts?  Sounds like a simple fan might be better than relying on convection?

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Posts: 2,240
Reply with quote  #4 
Right, the convection current will be pretty sluggish - no acceleration because not enough cold surface at the back of the room (no window in your lounge - that's why I suggested the fans...); so it can only leak into the corridor; you would have to help it along by causing a draft.

The gaps at the bottom of the sunspace window sound good. (You might need rodent- or reptile-protection on there ?).

The way around the bedroom window-opening scenario, might be to install a timer-controlled window fan or an HVAC flap in a blank… http://www.costco.com/Bionaire%C2%AE-Twin-Window-Fan.product.100110337.html

Alternatively, one of these – a lot dearer, but can be window or wall-mounted:
Failing this, if you have a feline, then a cat-flap might work: http://ecatdoors.blogspot.fr/2015/04/cat-mate-elite-id-disc-cat-flap-with.html

Regarding the garage: is it used as an actual garage (exhaust fumes etc.), caution is advisable – your local regs might not allow a direct draw into your house…
If the garage is disused or not used, or has been already converted, then the above might be non-issues...


(1)  "Heat goes from hot to cold, there is no directional bias"
(2) It's wrote, "voilà" unless talking musical instruments...

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Posts: 2,898
Reply with quote  #5 
A couple easy ways to do this... if you have central air/heat try putting the fan on "circulate" will move the air around.

Another method is to get some small "box" fans and put them in the doorways, blowing TOWARD the sunroom. They will extract the cool air near the floor, and warm air near the ceiling will flow into the room you want heated. It works better than you might think.

Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay

Posts: 9
Reply with quote  #6 
Nice tip. That's one I can try out with very little effort.

Sounds like I'll be playing around with fans and windows for a while [smile]
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